In recent years, attention is being given to the development of a next-generation electric power network referred to as “smart grid” that incorporates the means for automatically controlling supply of and demand for electric power into the power network. The smart grid controls the flow of electric power in the electric power network not only from the supply side but also from the demand side, to thereby optimize or balance supply of and demand for electric power.
One example is that batteries of electric motor vehicles owned by individual households can be used as the buffer for leveling demand for electric power by reducing its peak. For example, the peak of demand for electric power can be reduced if the electric power charged in the battery of the electric motor vehicle during periods of low demand for electric power, such as midnight, is used in the house during periods of peak demand for electric power. This also leads to a saving in electricity charges for individual households because the electricity charges for periods of low demand for electric power, such as midnight, are set to be lower than those for periods of high demand for electric power, such as daytime hours. The smart grid is intended for automatization of the above-described control of supply of and demand for electric power.
The electric power network managed by the smart grid is based on the assumption that batteries of electric motor vehicles are not only charged through the electric power supply from houses to the electric motor vehicles but also actively discharged through the electric power supply from the electric motor vehicles to the houses. Such flow of electric power is managed by an energy management system (EMS for short) provided for each customer.
For example, power generation installations such as photovoltaic power generation (PV for short) devices, predominantly large power load installations including electric water heaters and air conditioners, and electric storage installations such as batteries of vehicles are placed under the control of the EMS. The EMS controls the power generation installations, the power load installations, and the electric storage installations mentioned above such that the electric power demand is leveled. This works to balance supply of and demand for electric power, thereby cutting back the amount of electric power purchased from power companies.
Attempts are being made to improve the environmental performance of the whole society by expanding the target range of these techniques which has been within households. A start has been made at experiments and conceptual planning for equipping the commercial electric power network with the community energy management system (CEMS for short) with the objectives of leveling the electric power demand and balancing supply of and demand for electric power in each city and each town including customers in a neighborhood, such as neighboring houses and factories and buildings in the neighborhood.
Large-capacity batteries are used as the batteries to be mounted on electric motor vehicles in order to secure a range sufficient for users' daily traveling. The capacity of a battery to be mounted on an electric motor vehicle is so large that the electric power used by an ordinary household in several days can be provided by one electric motor vehicle. Thus, the availability of battery plays a big role in creating an electric power supply-and-demand managing plan for customers through the EMS.
However, the electric motor vehicle is used in the user's travel. Thus, while the user is traveling in the electric motor vehicle, the battery of the electric motor vehicle cannot be used for leveling the electric power demand in the house. The electric power stored in the battery is used for the traveling of the electric motor vehicle, so that the amount of electric power remaining in the battery (hereinafter also referred to as “battery remaining amount”) at the time of departure differs from that at the time of return. The user needs to store, before departure, electric power required for the traveling in the battery of the electric motor vehicle.
Thus, the EMS adapted to electric motor vehicles is required to create and manage a charging and discharging plan for the barriers of electric motor vehicles in consideration not only of the leveling of electric power demand based solely on the predictions about electric power use by customers but also of, for example, use plans for electric motor vehicles and conditions of electric motor vehicles (see, for example, Patent Document 1).
In a case where the traveling schedule, particularly the traveling route, of the electric motor vehicle is known in advance, the amount of battery electric power consumed by the motor during the traveling of the electric motor vehicle can be calculated from the traveling route and the amount of electric power required for the traveling distance measured in advance. The EMS adapted to the electric motor vehicle calculates the amount of battery electric power consumed during the traveling of the electric motor vehicle on the basis of the traveling schedule of the electric motor vehicle and creates, in advance, the charging and discharging plan with consideration given to the battery remaining amount at the time of return of the electric motor vehicle.
However, there is no guarantee that the electric motor vehicle travels on the route specified in advance. The electric motor vehicle sometimes does not return with the battery remaining amount that has been estimated in advance for the time of return as a result of, for example, traveling on a wrong route, electric power consumption caused by traffic congestion, or charging and discharging of the battery at a stopover point.
To cope with these cases, an electric motor vehicle management probe is mounted on each electric motor vehicle. The electric motor vehicle management probe measures the conditions of the electric motor vehicle (hereinafter also referred to as “vehicle conditions”) and transmits probe information being the measurement result to the EMS through communications. Thus, the idea of utilizing the probe information in the smart grid is under consideration (see, for example, Patent Document 2).